The objective of the proposed research is to study a new mutant line of chickens (DAM line), characterized by defective melanin pigmentation and serious visual problems, in order to determine its potential as a biomedically significant animal model for one or more human eye disorders. The postnatal development of a cutaneous amelanosis, resembling human vilitigo, is accompanied by reduced melanization of the choroid, and in approximately 40% of the line, retinal degeneration leading to apparent blindness. The eyes of blind, partially sighted and normal DAM's will be compared with light and electron microscopy techniques on the basis of morphological and pathological changes along with their neural and behavioral correlates, including an investigation of central nervous system projections. Comparative studies will also be conducted on melanocyte function and survival at the cutaneous level, particularly in the feather follicle. Particular attention will be paid to changes taking place during the period of melanocyte destruction in both ocular and cutaneous tissue. An attempt will also be made to determine the basic genetic defect responsible for the amelanosis and resulting eye damage. These studies will include tissue graft exchanges between amelanotics and normals following induced tolerance; studies on the role of the immune system by T and B cell elimination attempts; and histochemical studies associated with melanin synthesis by the defective melanocytes.